The proposed experiments investigate choice behavior. One group of experiments further assesses the PI's delay-reduction hypothesis of choice and conditioned reinforcement. Some of these experiments use the hypothesis as a guide to assess whether principles that have evolved from the study of decision making in the conditioning laboratory are consistent with decision making in situations that share important properties with naturally occurring foraging. Experiments in the first group investigate: varying the accessibility of the less profitable outcome on its acceptability in successive encounter procedures and in standard choice procedures; the adequacy of Killeen's incentive theory vs the delay-reduction hypothesis; the relation between choice, risk-aversion and economic context. The second group of experiments assess variables affecting observing by children, human adults and pigeons in standard laboratory tasks, in videogame playing and in health-related settings. We propose to investigate the effects of delayed reinforcement, superstitious responding, instructions, risk-aversion, economic context, whether observing obeys the same principles when subjects are losing rather than gaining points, and theories including Dinsmoor's selective observing hypothesis.